/*
 * Copyright 2019-2029 FISOK(www.fisok.cn).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package cn.fisok.raw.io;

import java.io.IOException;
import java.io.InputStream;

/**
 * @author : 杨松<yangsong158@qq.com>
 * @date : 2019/12/28 22:56
 * @desc : 二进制输出流
 */
public class ByteInputStream extends InputStream {
    /**
     * Our byte buffer
     */
    protected byte[] buf = null;

    /**
     * Number of bytes that we can read from the buffer
     */
    protected int count = 0;

    /**
     * Number of bytes that have been read from the buffer
     */
    protected int pos = 0;

    public ByteInputStream(byte[] buf, int count) {
        this.buf = buf;
        this.count = count;
    }

    public final int available() {
        return count - pos;
    }

    public final int read() {
        return (pos < count) ? (buf[pos++] & 0xff) : -1;
    }

    public final int read(byte[] b, int off, int len) {
        if (pos >= count)
            return -1;

        if ((pos + len) > count)
            len = (count - pos);

        System.arraycopy(buf, pos, b, off, len);
        pos += len;
        return len;
    }

    public final long skip(long n) {
        if ((pos + n) > count)
            n = count - pos;
        if (n < 0)
            return 0;
        pos += n;
        return n;
    }

    public void close() throws IOException {
        super.close();
        buf = null;
        count = 0;
    }

    public synchronized void reset() {
        pos = 0;
    }
}
